/*
 * Copyright 2002-2023 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.jdbc.datasource;

import com.kfyty.loveqq.framework.core.autoconfig.InitializingBean;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;

import javax.sql.DataSource;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.logging.Logger;

/**
 * JDBC {@link javax.sql.DataSource} implementation that delegates all calls
 * to a given target {@link javax.sql.DataSource}.
 *
 * <p>This class is meant to be subclassed, with subclasses overriding only
 * those methods (such as {@link #getConnection()}) that should not simply
 * delegate to the target DataSource.
 *
 * @author Juergen Hoeller
 * @see #getConnection
 * @since 1.1
 */
public class DelegatingDataSource implements DataSource, InitializingBean {
    @Nullable
    private DataSource targetDataSource;


    /**
     * Create a new DelegatingDataSource.
     *
     * @see #setTargetDataSource
     */
    public DelegatingDataSource() {
    }

    /**
     * Create a new DelegatingDataSource.
     *
     * @param targetDataSource the target DataSource
     */
    public DelegatingDataSource(DataSource targetDataSource) {
        setTargetDataSource(targetDataSource);
    }


    /**
     * Set the target DataSource that this DataSource should delegate to.
     */
    public void setTargetDataSource(@Nullable DataSource targetDataSource) {
        this.targetDataSource = targetDataSource;
    }

    /**
     * Return the target DataSource that this DataSource should delegate to.
     */
    @Nullable
    public DataSource getTargetDataSource() {
        return this.targetDataSource;
    }

    /**
     * Obtain the target {@code DataSource} for actual use (never {@code null}).
     *
     * @since 5.0
     */
    protected DataSource obtainTargetDataSource() {
        DataSource dataSource = getTargetDataSource();
        Assert.state(dataSource != null, "No 'targetDataSource' set");
        return dataSource;
    }

    @Override
    public void afterPropertiesSet() {
        if (getTargetDataSource() == null) {
            throw new IllegalArgumentException("Property 'targetDataSource' is required");
        }
    }


    @Override
    public Connection getConnection() throws SQLException {
        return obtainTargetDataSource().getConnection();
    }

    @Override
    public Connection getConnection(String username, String password) throws SQLException {
        return obtainTargetDataSource().getConnection(username, password);
    }

    @Override
    public int getLoginTimeout() throws SQLException {
        return obtainTargetDataSource().getLoginTimeout();
    }

    @Override
    public void setLoginTimeout(int seconds) throws SQLException {
        obtainTargetDataSource().setLoginTimeout(seconds);
    }

    @Override
    public PrintWriter getLogWriter() throws SQLException {
        return obtainTargetDataSource().getLogWriter();
    }

    @Override
    public void setLogWriter(PrintWriter out) throws SQLException {
        obtainTargetDataSource().setLogWriter(out);
    }

    @Override
    public Logger getParentLogger() {
        return Logger.getLogger(Logger.GLOBAL_LOGGER_NAME);
    }

    @Override
    @SuppressWarnings("unchecked")
    public <T> T unwrap(Class<T> iface) throws SQLException {
        if (iface.isInstance(this)) {
            return (T) this;
        }
        return obtainTargetDataSource().unwrap(iface);
    }

    @Override
    public boolean isWrapperFor(Class<?> iface) throws SQLException {
        return (iface.isInstance(this) || obtainTargetDataSource().isWrapperFor(iface));
    }
}
